CAREER: Hybrid Surface Coating Toward Corrosion-Controlled Magnesium-Based Implants

About This Grant

NON-TECHNICAL SUMMARY There is an increasing incidence of bone fractures in the United States, which is caused in part by an aging population. The global market for fracture fixation devices (e.g., medical implants) is expected to reach $13.6 billion by 2027, growing at a compound annual growth rate of 6.1% over that time. This Faculty Early Career Development (CAREER) award addresses a significant healthcare challenge by enhancing the clinical feasibility of biodegradable magnesium-based metallic implants. The utilization of biodegradable implants in biomedical applications, including vascular stents and small bone fixation devices, presents an innovative alternative to the currently employed permanent metallic implants. These permanent metallic implants often entail significant complications and may necessitate surgical intervention. Although biodegradable magnesium-based implants hold promise, their rapid degradation undermines their efficacy before the completion of the healing process. This project introduces innovative hybrid coatings, combining different coating methods and materials, to mitigate degradation and allow the controlled release of bioactive agents. By investigating how bioactive agents interact with coated magnesium, the project aims to understand degradation inhibition mechanisms and modulate degradation rates. Additionally, a computational model will be developed to predict degradation and agent release, bridging theory and experiment. The significance of this research lies in its potential to revolutionize patient-specific biomedical implants by tailoring the degradation rates and hence the lifespan of an implant. Successful outcomes may lead to the improvement of a variety of implants including orthopedic, facial, oral, and more, benefiting patients with personalized needs. This project aligns with the NSF's mission by advancing science, promoting health, and contributing to national welfare. Recognizing the underrepresentation of certain groups, the project includes a community-based mentoring program that aims to expose underserved Hispanic children in Chattanooga and the Southeast Tennessee Area to STEM through hands-on activities, fostering engagement and civic involvement. The PI also plans to work with the Society of Women Engineers at the university to introduce female high school students to biomedical engineering research, encouraging their participation in STEM fields. Moreover, a graduate course on "Manufacturing of Biomaterials" will be developed, enriching education and nurturing future professionals. TECHNICAL SUMMARY This research project addresses the challenge of rapid degradation in magnesium-based biomedical implants, hindering their clinical impact. By employing hybrid coating systems, particularly plasma electrolytic oxidation (PEO) coupled with the sol-gel coating method, the project aims to control degradation rates and enhance bioactive agent release for smart biomaterials. This research project will address gaps in understanding the mechanisms behind enhanced corrosion resistance of coated magnesium implants and the effective regulation of bioactive agent release during prolonged implantation periods. Two primary objectives guide the investigation: Objective #1 focuses on understanding the interaction of bioactive agents with the porous surface of PEO-coated magnesium substrates, elucidating their role as corrosion inhibitors through microstructural evolution and electrochemical corrosion mechanisms. Objective #2 involves the development of a versatile numerical model based on a physical modeling approach to predict degradation rates and bioactive agent release from magnesium substrates coated with hybrid PEO-based and multiple layers of hydroxyapatite (HA) sol-gel coatings. One outcome of the project is the possibility of depositing thin (< 100 nm) subsequent coating layers. That enables the establishment of a clear relationship between the deposited coating layers and degradation rates. This understanding is crucial for ensuring a time-certain commencement of the implant’s degradation, a vital aspect for patient-specific implant applications. The interdisciplinary approach combines expertise in biomaterials processing, corrosion science, and numerical modeling. The anticipated outcomes hold the potential to integrate magnesium as a biodegradable metal technology in clinical settings, particularly for patient-specific devices in orthopedic and craniomaxillofacial applications. The educational objective of the project is to (1) develop a new community-based mentoring program for Hispanic children ages 11 to 18, (2) organize talks, presentations, and live demonstrations aiming at recruiting more female research students, and (3) develop a graduate interdisciplinary course on the topic of “Manufacturing of Biomaterials”. These educational activities will offer STEM exposure, social engagement, career development, and advising, particularly for Hispanic and female students in Chattanooga and the Southeast Tennessee Area. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.